It is common to equip walk-behind implements, such as lawn mowers, rotor tillers and lawn edgers, with wheels driven by an engine. In many such implements, the drive wheels are powered through a V-belt connection between the engine and a transmission.
One difficulty often encountered with such V-belt drive arrangements occurs when the operator is trimming around bushes, hedges and other areas where he occasionally will want to pull the implement back and then let it proceed ahead.
Many mowers and similar implements with V-belt drives have transmissions in which the axle, gears and driven V-belt sheave all rotate in reverse when the wheels are turned rearwardly. Since this condition exists even when the V-belt drive is disengaged, there will be considerable drag on the wheels as the driven V-belt sheave is rotated in reverse against the V-belt's resistance.
One attempt to overcome this problem is provided in a mower which utilizes a transmission equipped with a ball clutch and means for clutching and unclutching the V-belt drive. The ball clutch couples the input pulley shaft to the drive wheel axle, making it possible for the operator to de-couple the axle from the transmission before the machine is moved rearwardly, thereby permitting the axle to freewheel and eliminating back drive of the transmission elements.
Such a control mechanism is illustrated in this Application in FIGS. 2 and 3. FIG. 2 illustrates this mechanism in its disengaged position and FIG. 3 illustrates it in its engaged position. To drivingly power the V-belt 10, a belt tightener arrangement is interposed between the engine or drive pulley 12 and the transmission 14 and its driven pulley 16. The tightener includes a set of sheaves or set of pulleys 18 and 20 around which the V-belt 10 is trained. The pulleys 18 and 20 are mounted on an idler bracket 22 carried on a pivot structure 24 mounted on the mower housing 26. The transmission 14, a Kanzaki Tuff Torq, is equipped with a separate lever 28 for engaging and disengaging its ball clutch. A shifter rod 30, taking the form of an elongated wire, is connected between the belt tightener idler bracket 22 and the ball clutch lever 28 so that movement of the rod 30 by the operator simultaneously activates the ball clutch and tightens the V-belt 10 around the drive and driven pulleys 12 and 16.
This arrangement provides for simultaneous activation of the ball clutch and a V-belt clutch. Occasionally, however, the V-belt clutch may become fully engaged prior to engagement of the ball clutch causing the drive wheels to not be engaged as smoothly as desired.
An additional problem with this control mechanism arises when adjustment of the shifter rod in the idler bracket is required due to belt wear. As the V-belt wears, the belt tightener bracket has to be rotated about its pivot point through a greater arc to tighten the belts. Since the new arc swung by the adjusted idler bracket is increased as this adjustment is made and the arc through which the ball clutch lever is moved does not need to be increased, the length of the shifter rod must be adjusted. To permit this adjustment, slots are provided in the idler bracket. If the operator did not make this adjustment as belt wear occurred, the shifter rod would deflect or bend as the operator tried to engage the V-belt drive.
Since multiple parts are required with this control mechanism, manufacturing and repair costs are incurred that would be higher than those costs associated with a fewer number of parts.